RESUMO
OBJECTIVE: Ascorbic acid represents one of the most important antioxidants and neuromodulators, and plays an important role in the cerebral system. In the present study, we investigated the central effect of ascorbic acid on fluid regulation and electrolyte homeostasis. METHODS: Male Wistar rats were implanted with stainless steel cannulas into the lateral ventricle, and sodiun excretion and urinary volume were measured after intracerebroventricular (i.c.v.) injection of ascorbic acid (200 or 600 nmol/rat). In another set of experiments, vasopressin and oxytocin plasma levels were evaluated 10, 20 and 30 minutes after ascorbic acid i.c.v. injection. RESULTS: The administration of ascorbic acid to conscious rats resulted in a significant decrease in urinary volume and an increase in the renal excretion of sodium, with a concomitant increase in the plasma levels of vasopressin and oxytocin. CONCLUSIONS: These results suggest that ascorbic acid may play a significant role in the central regulation of fluid and electrolyte homeostasis.
Assuntos
Ácido Ascórbico/administração & dosagem , Natriurese/efeitos dos fármacos , Hormônios Neuro-Hipofisários/metabolismo , Micção/efeitos dos fármacos , Animais , Antidiuréticos/administração & dosagem , Sistema Nervoso Central/efeitos dos fármacos , Estado de Consciência , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Injeções Intraventriculares , Masculino , Ocitocina/sangue , Hormônios Neuro-Hipofisários/sangue , Ratos , Ratos Wistar , Regulação para Cima/efeitos dos fármacos , Vasopressinas/sangue , Equilíbrio Hidroeletrolítico/efeitos dos fármacosRESUMO
1. Bothrops jararaca plasma or serum hydrolysed L-cystine-di-beta-naphthylamide (CNAse activity) at a degree comparable to that of plasma or serum in pregnant women. 2. In adult snakes, activity was less in males. It was not altered in pregnancy but increased after delivery, being higher at pH 6.4 (unspecific enzymes) than at pH 7.9 (true pregnant woman plasma oxytocinase). 3. Its optimum pH was 5.9, different from that of other known enzymes that hydrolyse the same substrate. 4. Bothrops jararaca plasma also hydrolysed vasopressin, oxytocin and vasotocin. 5. These hydrolysing activities were unexpected for an ovoviviparous reptile.